[llvm] [LV] Autovectorization for the all-in-one histogram intrinsic (PR #91458)

[Graham Hunter via llvm-commits]

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@@ -144,7 +144,9 @@ class MemoryDepChecker {
       // on MinDepDistBytes.
       BackwardVectorizable,
       // Same, but may prevent store-to-load forwarding.
-      BackwardVectorizableButPreventsForwarding
+      BackwardVectorizableButPreventsForwarding,
+      // Access is to a loop loaded value, but is part of a histogram operation.
+      Histogram
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huntergr-arm wrote:

I've added a separate interface (canVectorizeMemoryWithHistogram), along with a flag to enable vectorization of histograms. Currently off by default.

https://github.com/llvm/llvm-project/pull/91458